1. Technical Field
This invention generally relates to infusion pump systems. More particularly, this invention relates to infusion pump systems having vacuum assist mechanisms for preventing vacuum stall during infusion.
2. Description of the Related Art
Means for supplying patients with fluid medication for sustained periods in a controlled manner is well known in the art. One such commonly known and well recognized means is a bag filled with fluid medication which was fed into the patient by gravitational force through intravenous tubing having drip or other controllers. More specifically, a sterile container such as a glass or plastic bottle, or a plastic bag was attached to one end of a drip chamber, and the other end of the same was attached to a tube. The drip chamber allowed the fluid to flow one drop at a time, and the tube had an attached hollow needle that was inserted into the vein. Further connectors could be attached to the tube, which permitted other fluid medication to be delivered through the same needle. The adjustability of the flow rate in such prior devices was quite limited, however, and a variety of expensive and complicated flow control valves and devices have been developed. Where fluctuations in the flow rate were not critical, the aforementioned gravity drip system continues to be used for its utter simplicity.
In an attempt to obtain even greater control over the flow rate, peristaltic and other electrically driven pumps were developed. Conventional peristaltic pumps typically have a section of resilient tubing positioned between a wall and a set of rollers or reciprocating pushers that progressively compress sections of tubing to facilitate the pumping of a liquid therethrough. Such peristaltic pumps known in the art include teachings from U.S. Pat. No. 2,877,714 to Sorg, et al. Improvements thereto have also been made, such as those teachings of a curvilinear peristaltic pump in U.S. Pat. No. 6,371,732 to Moubayed, et al., which is wholly incorporated by reference herein.
In many situations, the aforementioned elastic bags filled with fluid medication were used with peristaltic pumps. However, there were other instances where a syringe containing fluid medication was preferable, referred to in the art as “IV push.” As will be appreciated by a person of ordinary skill, the use of peristaltic pumps for IV push caused a peculiar situation known as vacuum stall. As the fluid medication was extracted from the syringe, a vacuum was created therein by the pressure difference between the inside and the outside of the syringe. Essentially, as the amount of fluid was decreased inside the syringe, the space occupied by that fluid was decreased at a reduced rate, creating a vacuum. With more fluid being extracted from the syringe, the force required to extract the same became greater, eventually reaching a point where the peristaltic pump could not overcome the vacuum force. Upon reaching this point, no further infusion was possible.
Accordingly, what is needed in the art is a vacuum assist system for preventing vacuum stall when using syringes with peristaltic pumps for infusing a fluid medication into a patient. Additionally, there is a need for a mechanical syringe assist device which is capable of applying a compressive force upon a conventional syringe. What is also needed in the art is an apparatus which can hold the peristaltic pump, the syringe, and a vacuum assist device as a single unit, and which can be attached to a pole or hung from a variety of structures. These needs and more are met and with the present invention, the details of which are discussed more fully hereunder.